The Britons were an ancient Celtic people who lived in Great Britain from the Iron Age through the Roman and Sub-Roman periods. They spoke a language that is now known as Common Brittonic.

The earliest evidence of the existence of the Britons and their language in historical sources dates to the Iron Age. After the Roman conquest of Britain in the 1st century, a Romano-British culture emerged, and Latin and British Vulgar Latin coexisted with Brittonic. During and after the Roman era, the Britons lived throughout Britain south of the Firth of Forth. Their relationship with the Picts, who lived north of the Firth of Forth, has been the subject of much discussion, though most scholars accept that the Pictish language was related to Common Brittonic.